El Nino Update: Rain in the South, but What about the North?

The winter of 2015-16 is still on track to have one of the strongest El Niños on record, and the question is no longer whether there will be a strong El Nino, but what effects will it bring to the United States. Forecasters for NOAA’s Climate Prediction Center (CPC) just issued their Winter Outlook (for the months of December, January and February), and they are looking for a good chance of above average rainfall for about the southern third of the conterminous states. This makes the prospects good for at least partial relief for the drought in California, but strong El Ninos bring the risk of dangerous and destructive flooding to the region.

The situation is a bit murkier for the Pacific Northwest, also in the midst of a drought and plagued by numerous large fires this year. The CPC outlook is diffident on the subject, predicting equal chances of being wetter or drier than normal for part of the area, trending toward more likely drier than normal in Idaho and Montana.

us-winter-outlook

One clue might come from the NOAA’s Climate Forecast System version 2, or CFSv2. Looking at the current winter forecast from the CFSv2 we see that the coastal Pacific Northwest is forecast to also have above average precipitation during the winter.

seasonal

Unfortunately, there is one very serious caveat to this forecast: the CFSv2 has very little skill forecasting precipitation in that region during winter; on the other hand the CFSv2 does have good skill forecasting for California. Of course, that could be at least one reason that the CPC forecast is a toss-up, while they’re confident in above average rainfall for Southern California.